Within an engine compartment of a vehicle, there are disposed an engine and parts of the intake system such as an air cleaner. In a conventional arrangement as shown in FIG. 10, there are disposed an engine 302, an intake manifold 304 attached to the engine 302, a surge tank 306 connected to the intake manifold 304, and a throttle body 308 attached to the surge tank 306. On a side fixed to the vehicle body, there are disposed an air cleaner 310 and a resonator 314 connected to the air cleaner 310 through an intake pipe 312. The resonator 314 is connected with an intake nozzle 316. Further, the air cleaner 310 and the throttle body 308 are connected by a connection hose 320 formed with an accordion portion 318. The connection hose 320 is flexible to absorb vibration and relative movement at the accordion portion 318.
In the conventional intake system of an engine, the lengths and diameters of the intake pipe and the connection hose, as well as the capacities of the resonator and the air cleaner, are determined in order to obtain a satisfactory output performance and a noise performance of the engine, and therefore a large space has been required to lay out these parts of the intake system. The large area taken up by the prior art intake system is a disadvantage. As shown in FIG. 10, the resonator 314 and the air cleaner 310 are fixedly installed on the vehicle body side, and hence there has been difficulty in that vibrations due to pulsating motions of these parts are easily propagated from the air cleaner side to the vehicle body side.
Since the engine causes vibrations and shakings, it has been necessary to use a connection hose formed with an accordion rubber hose for connecting the engine with the air cleaner fixed to the side of the vehicle body. This creates difficulties, however, since the connection hose is liable to break, and a large-sized connection hose has to be used because of the accordion form and accordingly its outer diameter is undesirably large.
Further, in the process of assembling the parts of the intake system to an internal combustion engine at the factory, a processing step is required to connect the air cleaner to the connection hose after the engine has been mounted in the vehicle body. The overall assembling process is accordingly increased.